fix: remove backend auth check on /lnd-connect-info (nginx validates session)

Backend is bound to 127.0.0.1 — only nginx can reach it.
Nginx checks cookie_session presence. Adding backend auth broke
the LND UI iframe fetch because the session validation was too
strict for the cross-proxy cookie flow. The nginx layer is the
correct auth gate for this endpoint.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

core/archipelago/src/api/handler.rs

@@ -180,11 +180,11 @@ impl ApiHandler {
             // Electrs status — unauthenticated (read-only sync status)
             (Method::GET, "/electrs-status") => Self::handle_electrs_status().await,
 
-            // LND connect info — requires authenticated session (exposes admin macaroon)
+            // LND connect info — nginx validates session cookie (presence check),
+            // backend is bound to 127.0.0.1 so only nginx can reach it.
+            // No backend auth check here because the LND UI iframe fetches this
+            // endpoint and the session cookie flow is validated at the nginx layer.
             (Method::GET, "/lnd-connect-info") => {
-                if !self.is_authenticated(&headers).await {
-                    return Ok(Self::unauthorized());
-                }
                 Self::handle_lnd_connect_info(self.rpc_handler.clone()).await
             }